The present invention relates to an improvement in the shaping of slit segments of meshes formed in deformable strip and, in particular, relates to an improvement in the method and apparatus of copending Canadian Patent Application No. 315,190 filed Oct. 31, 1978 wherein a concurrent slitting and preforming operation provides a plurality of longitudinally extending strand-like components comprising segments elongated by deformation out of the plane of the strip and unslit segments retained in the plane of the strip. The unslit segments together define continuous bands extending laterally across the portion of strip contained between longitudinally extending edge portions of strip. In a second slitting step, the slits are extended in a staggered relation to permit lateral expansion of the slit portion of the strip. Opposite longitudinally extending edges of the strip are then drawn apart to expand the slit and preformed strip to form sheet having a network of meshes which are substantially in the plane of the sheet. Because of the holding of the bands containing all the bonds which connect adjacent components during slit segment elongation, desired elongation of the slit segments as they are formed is achieved while rupture of the strands during mesh expansion or failure of the strands at node bonds is substantially avoided.
In known methods for elongating slit segments so that mesh areas do not become shorter than unslit borders on lateral expansion, e.g. the preforming of wires from strip having conventionally staggered rows of slit as in U.S. Pat. No. 1,212,963, the wires are shaped against symmetrically contoured tool faces. This patent is directed to the production of metal lath, and it is unlikely that stretching of the wires during preforming of metal suitable for this purpose would cause localized weakening that may affect their usefulness.